IT8148262A1 - HYGIENIC ITEMS FOR PERSONAL USE IN PARTICULAR ABSORBENT PAD AND DISPOSABLE DIAPERS WITH THERMALLY FUSIBLE DIAPHRAGM - Google Patents

Description

DESCRIPTION

of the invention entitled: "HYGIENIC ARTICLES FOR PERSONAL LEO, IN PARTICULAR ABSORBENT PAD AND SINGLE-USE DIAPERS. USE WITH A THERMALLY FUSIBLE DIAPHRAGM"

SUMMARY

A sanitary article, e.g., a disposable absorbent pad, is provided with an absorbent matrix and a fluid-impermeable diaphragm. A portion of this diaphragm consists of a thermally fusible sheet fused to the absorbent component. The absorbent component may have thermally fusible material interdispersed within it and have a fluid-permeable top layer essentially coterminous with or wrapped around the absorbent component and the absorbent-diaphragm combination. If a fluid-permeable liner is used, it is preferable to have a fusible material fused to the diaphragm. The fusion is preferably carried out in irregularly distributed areas across the surface of the sanitary article, for example by embossing.

This invention relates to sanitary articles for personal use, such as tampons, disposable sanitary napkins, and in particular sanitary articles comprising fluid-permeable diaphragms.

TECHNOLOGY OF INVENTION.

Disposable absorbent, hygienic, and other such articles contain an absorbent medium designed to retain exudates and secretions from the human body and a fluid-impermeable liner to prevent the passage of fluids through the absorbent material. In some cases, such hygienic articles also include a fluid-permeable top layer to protect the source of the fluid, such as a wrapping surface or a component located on the outside of the pad in direct contact with the absorbent material. The inclusion of such a layer is desirable to prevent the penetration of the absorbent material into the wrapping surface or into a body opening.

Disposable, hygienic, absorbent pads have been produced in the past with various structures in which the fluid-impermeable diaphragm is always secured to the pad with adhesives. For example, the disposable hygienic pads currently sold under the brand name NEW FREEDCM by Kimberly-Clark Corporation utilize a fluid-impermeable liner that completely surrounds the absorbent matrix. The overlay liner is sealed with a smear of adhesive that penetrates the overlay. Between the absorbent matrix and the fluid-permeable liner is a fluid-impermeable diaphragm that is adhered to the liner by conventional means and adhesives. Another type of structure known in the prior art is described in general terms in U.S. Patent 4,079,339 issued to Howard A. Whitehead and assigned to Kimberly-Clark Corporation. This patent describes a tampon.

of defined dimensions employing adjacent layers of absorbent and a diaphragm and, in one embodiment, a fluid-permeable outer covering. In this particular patent, the integrity of the absorbent is maintained by compressing a separate sample along its surface. This integrity is, of course, important in cases where no permeable covering is used. The diaphragm is adhesively secured to the absorbent portion. Other pads have been developed in which the impermeable diaphragm covers the side and, in some cases, upper portions of the absorbent, but, since it is desired to maintain the positional relationship between the diaphragm and the absorbent matrix, it has been necessary to adhesively secure the diaphragm to the absorbent matrix at least in a portion of the surface where overlap exists.

The inclusion of the adhesive entails several disadvantages both for the product and its manufacturing. First of all, regarding the product, the inclusion of the adhesive introduces undesirable stiffness and a loss of the perceived softness in sanitary pads or any other hygienic article of the gBOBre. As for manufacturing, applying the adhesive requires an additional operation that complicates and slows down the production cycle and increases its cost.

SUMMARY OF THE INVENTION

According to this invention, the problems inherent in the adhesive attachment of the diaphragm to the matrix as a Barrel or an Ionic Arrtinn1n of the type cited are eliminated by using a diaphragm with at least a two-layer system, at least one of which makes the diaphragm hot-meltable.

According to the invention, the diaphragm is made up of at least two layers of different materials. One of these is a thermoplastic material with a melting temperature much lower than that of the other layer. For the purposes of this invention, the fusible component must melt with the absorbent matrix at a temperature lower than approximately 180°C, i.e., a high thermal degradation temperature for the cellulose. While cellulose tends to degrade between 150°C and 200°C, there is a substantial loss of absorbent power at approximately 180°C and 200°C. Cellulose components are usually used in sanitary articles, particularly in absorbent tampons and diapers, as at least part of the absorbent layer. The limit of 180°C is a very precise figure. Obviously, in the case of sanitary towels that do not contain cellulose or materials derived from it, the fusible part is subject to redefinition due to the undesirable thermal degradation of such products. Typically, such a diaphragm is obtained by construing thermoplastic materials. These thin-layer films are currently available under the designation CROWN ZEELON from Crown Zel-lerbach Corp. In this patent, an ethylene-propylene block polymer is coextruded with low-density polyethylene. Other coextruded films containing at least two layers of thermoplastic materials with widely differing melting temperatures are also suitable.

While coextrusion is a suitable method for producing two- or three-layer composite sheets of polymers with different melting characteristics, as disclosed in U.S. Pat. No. 3,843,478, it is not the only method for producing such sheets. An alternative is to mold a high-melting polymer and then melt a lower-melting polymer in sheet form to the surface or surfaces of the higher-melting polymer. This method of molding multi-layer polymer composites is well known and need not be described in detail here.

With respect to melting, bonding is substantially enhanced if the absorbent layer contains at least some additional fusible material. This material can be directed onto the portion of the layer in contact with the fusible surface of the diaphragm or dispersed throughout the absorbent matrix.

When the fusible material is present in the absorbent matrix, the maximum temperature is a function of that necessary to produce a certain degree of fusion between the fusible material, r -' - --?

the absorbent material and the fusible component of the diaphragm. This temperature can be substantially lower than 180°C. In fact, if a fusible material is present, the melting temperature can be substantially lower than 180°C and decrease to as low as 90°C.

Examples of suitable fusible materials are ethylene-vinyl acetate copolymers such as those having a vinyl acetate content of 3-2.0% and a melting point of 90-110°C; ethylene-acrylic acid copolymer having a melting point between 80°C and 110°C; and low-density polyethylene with a melting point of 110-130°C. Higher-melting point polymers that may be used as the fusible component of the diaphragm when woven with the films already described may include, for example, high-density polyethylene with a melting point of 130-140°C; polypropylene with a melting point of 135-150°C; polybutylene with a melting point of 125-135°C; various nylons with a melting point of 210-240?C; polyesters, with a melting point of 150-180?C; polyurethanes with a melting point of 150-180?C; and polycarbonates with a melting point of 190-210?C. It is evident that once the choice of the fusible component has been made, the designation of a suitable component with a higher melting temperature occurs on the basis of the melting point of the fusible component.

When a thermoplastic fusible material is present as a component of the absorbent, the absorbent fuses to the diaphragm.

is obtained rapidly, for example by using hot embossing rollers. Localized points of contact, in some cases irregularly distributed along the surface B through the thickness of the pad, ensure sufficient adhesion to secure the pad to the plastic diaphragm CD. The embossing marks may have any particular configuration and be chosen to be straight-path as required. It should be noted that the principle of intermixing fusible fibers with cellulose fibers is well known. A particular variant is described in U.S. Pat. No. 4,198,324 to Anderson, B.t. al. and concerns a mixture of melt-blown thermoplastic fibers and conventional cellulose fibers laid down as an integral backing. The embossing of an integral combination of fusible and non-fusible fibers produces localized absorbability retarding or fluid-impermeable zones. Consequently, it is preferred that these zones are spaced apart.

you irregularly.and occupy no more than ICt-15% of the surface development of the absorbent pad,_

A particularly desirable variant of the principle of the invention consists in using a three-component compound, of which the Birio compound has the rough finish already described and thus ensures a rough friction surface so as to avoid conventional adhesive attachment of the pad to the panties. The type of finish produced could in practice be

. " . I

It can be obtained on the non-fusible part of the sheet, but this theory is indeed more difficult. The method according to the invention, in its most simple form, concerns only the fusion of the absorbent material with the fusible component in the fusible state of the diaphragm. Variations of this method allow for the particular design of the hygienic absorbent pad desired, i.e. two fusible surfaces can be arranged on the diaphragm in the case of a pad having a fusible layer in contact with the body which serves as an overcoat. In this case, the absorbent material is fused to one fusible surface of the fluid-impermeable diaphragm and the overcoat is fused to the second fusible surface of the diaphragm. This can be done in a single operation after the diaphragm has been placed on the absorbent material and the overcoat is fused to the second fusible surface of the diaphragm. This can be done in a single operation after the diaphragm has been placed on the absorbent material and the overcoat is fused to the second fusible surface of the diaphragm. has been applied to the diaphragm portion. As stated in relation to the absorbent sanitary pad, embossing is the preferred method to allow the necessary fixation for fusion. The melting temperatures, as stated above, depend on the nature of the fusible surface of the diaphragm, the fusible component of the pad, and the fusible overlay when used. Examples of specific embodiments of the absorbent pad according to the invention are given in the drawings described below. These examples, as can be deduced from the preceding description, are simple illustrations of some forms of use of the general principle of the invention and represent preferred, but not exclusive, forms of implementation.

DESCRIPTION OF THE DRAWINGS

Examples of preferred embodiments of the invention will be clearly evident from the accompanying drawings in which Figs. 1, 3, 4, 5 and 6 are transverse lateral sections of different embodiments of the invention, while Fig. 2 is a lateral perspective view of an absorbent pad with its covering according to the invention and Fig. 3 is a partially transversely sectioned plan according to another embodiment of the invention.

As can be seen in Fig. 1, an absorbent matrix 10 is surrounded by a fluid-permeable layer 14 in contact with the body. At the bottom of the pad is a diaphragm 11, consisting of a fusible layer 11a and a non-fusible layer 11b. An adhesive strip 12 is used to seal the edge of the body-contacting layer 14 in the corresponding overlap area to provide an adhesive surface for attaching the panties after the disengagement layer 13 has been removed.

Fig. 2 illustrates a typical absorbent swab configuration, representative of this broad class of hygienic swabs.

Fig. 3 is identical to Fig. 1 in all respects except that layers 11a and 11b are reversed and, in this case, the fusible coating 14 is fused to the fusible layer 11a of the diaphragm. This embodiment is particularly preferred when there is no fusible material scattered throughout the absorber.

Another absorbent pad with a coating is shown in Fig. 5. In this figure, the fluid-permeable fusible coating completely surrounds only the absorbent material and is fused to the fusible surface 11a of the diaphragm external to the other components of the pad. In Fig. 5, a third layer 11c is shown, which provides a rough friction surface for attachment of the pad to women's clothing. The absorbent matrix 10 in Fig. 5 contains fusible fibers, but as in the embodiment of Fig. 3, fusion occurs without the presence of such fibers.

However, if embossing is required as opposed to substantially greater heat application and total melting, fusible fibers must be present in the matrix. Figures 4 and 5 are examples of the sandwich structure found in some absorbent pads. The difference between these two figures is the presence, in Figure 6, of a third, rough layer 11C for securing the pad, while in Figure 4 a modified, printed, non-fusible layer serves the same function. As can be seen in the figure, the absorbent material 10a contains fusible filaments 10b. In this particular configuration, the pad is fused directly to the fusible diaphragm. The function of the pad is to fuse the pad directly to the fusible diaphragm.

1. A multi-layer hygienic article comprising a fluid-permeable layer in contact with the body, an absorbent layer, and a fluid-impermeable diaphragm having at least two layers of material with at least one of them being thermoplastic, fusible below approximately 18°C and the other non-fusible at temperatures higher than the first of the three layers.

2. Diaper comprising a fluid-permeable layer in contact with the body, an absorbent layer and a fluid-impermeable membrane having at least two layers of material, at least one of which is thermoplastic, fusible at a temperature lower than approximately 100°C and the other non-fusible at temperatures higher than the first of two layers.

3. A disposable, hygienic, absorbent pad comprising a fluid-permeable layer in contact with the body, an absorbent layer, and a fluid-impermeable diaphragm having at least two layers, one of which is fusible below approximately 1°C and the other is non-fusible at temperatures higher than the first of said layers.

4. A sanitary absorbent pad according to claim 3 wherein one of said sheets is fused to the absorbent layer.

5. A sanitary absorbent pad according to claim 3 or 4 wherein said absorbent layer comprises a fusible thermoplastic material.

6. An absorbent pad according to claim 3 or 4, wherein a fluid-permeable layer in contact with the body is fused to the diaphragm. 7. A disposable absorbent/hygienic pad comprising a fluid-permeable sheet in contact with the body, an absorbent layer, and a diaphragm having at least two layers, one of which is fusible at approximately 100°C and the other is non-fusible at temperatures higher than at least one of said layers, said fusible layers being affixed to said cyphragm.

8. Absorbent pad according to claim 7, in which the layer in contact with the body covers the diaphragm.

__S. raspberry.absorbent according to claim 3_wherein.the.body-contacting.anti-layer.has.at.least.one.adhesive.stripe.and.a.release.element.secured.thereto.for.adhesion.to.the.undergarment.

10. An absorbent pad according to claims 1, 3, or 7, wherein the diaphragm has a third layer in contact with the undergarment, provided with a friction surface intended to contact it.

11. An absorbent pad according to claims 1, 3 - 7 wherein the layer in contact with the body is absorbent.

12. Absorbent pad according to claims 1, 3 or 7, wherein the absorbent material contains interdispersed fusible material... . . . . _ _ _ _ .13. Disposable sanitary absorbent pad comprising an absorbent layer with interdispersed fusible material and a diaphragm with at least two layers, one of which is fusible at temperatures not exceeding that necessary to melt the fusible material in the absorbent. _ _ . _ _

14..Absorbent pad according to claims 1, 3, 4, 7, 8 - 13 wherein at least the absorbent portion of the pad has an embossed design..

15. A method for preparing a disposable hygienic absorbent pad with an absorbent layer containing fusible material and a diaphragm with at least two layers, one of which is fusible at temperatures not exceeding the melting temperature of the fusible material present in the pad, said method comprising fusing said layers to said absorbent material.

16. A method of preparing a disposable hygienic absorbent pad having a fusible fluid-permeable liner, an absorbent wrapped by said liner, and a fluid-impermeable diaphragm having at least two layers, one of which is thermally fusible at temperatures not exceeding the melting point of the wrapper, said method comprising fusing said fusible layer to said liner.

17. The method of claim 16 wherein the coating covers the diaphragm...

1B. The method of claim 16 wherein there are two thermally fusible layers on the diaphragm and the absorbent contains thermally fusible material and one layer is fused to the coating while the other is fused to the absorbent.

19. Method according to claims 15, 16, 17 or 1B wherein the melting is obtained by embossing.

20. A method according to claims 15, 16, 17 or 10 wherein the melt is produced in a sparse pattern on the surface of the pad.

21. Method according to claims 15, 16, 17 or 18 in which the casting is produced according to a dissected surface on more than 10% of the surface.